SEATTLE — Washington Gov. Jay Inslee has signed a group of bills tightening rules on guns in some circumstances, including targeting ghost guns and people found incompetent to stand trial.

Other measures in the group, which Inslee signed Tuesday, affect gun rights for people being released from short-term psychiatric holds, and people under restraining orders.

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Gun policy watchers have said the measures fit into a broader pattern that has seen gun control advocates cooling on efforts to broadly reform gun possession rights, and focusing on measures tailored to specific types of gun violence. Critics say the Washington bills collectively weaken gun rights in the state.

The so-called "ghost gun" measure targets two types of weapons: Plastic weapons printed on 3D printers, invisible to airport scanners, and guns without serial numbers, including guns that can be made from do-it-yourself kits available online without a background check.

The law bans outright undetectable guns and limits — but not ban — untraceable guns.

Specifically outlawed is any firearm that doesn't contain at least 3.7 ounces of steel, and any gun that wouldn't show a recognizable outline in an X-ray machine.

That essentially prohibits printing complete plastic guns on 3D printers, unless metal parts were included.

The law stops short of banning untraceable guns, defined as guns without a serial number from a federally licensed firearm manufacturer.

Making untraceable guns for personal use is allowed within certain limits under federal law.